Barium concentrations were measured on 17 pore fluid and 13 sediment samples from Sites 1253 and 1254 drilled offshore Costa Rica during Ocean Drilling Program (ODP) Leg 205. An additional 83 pore fluid and 29 sediment samples were analyzed for Ba concentrations from Sites 1039 and 1040 drilled during ODP Leg 170 offshore Costa Rica. Sites 1039/1253 and 1040/1254 are part of a transect across the Middle America Trench offshore Nicoya Peninsula. The entire incoming sediment section is being underthrust beneath the margin, providing an ideal setting to examine Ba cycling in the shallow levels of the subduction zone. Results from these analyses indicate that a significant amount of Ba is liberated from the mineral barite (BaSO4) in the uppermost hemipelagic sediments arcward of the trench. The shallow distillation of Ba may impact the amount of sedimentary Ba reaching the deeper subduction zone.
1Solomon, E.A., Kastner, M., and Robertson, G., 2006. Barium cycling at the Costa Rica convergent margin. In Morris, J.D., Villinger, H.W., and Klaus, A. (Eds.), Proc. ODP, Sci. Results, 205 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/205_SR/210/210.htm>. [Cited YYYY-MM-DD]
2Scripps Institution of Oceanography, University of California San Diego, 9500 Gillman Drive, La Jolla CA 92093-0212, USA. Correspondence author: esolomon@ucsd.edu
Initial receipt: 8 March 2005
Acceptance: 22 November 2005
Web publication: 4 April 2006
Ms 205SR-210